diff --git a/source/isaaclab_visualizers/test/conftest.py b/source/isaaclab_visualizers/test/conftest.py
new file mode 100644
index 000000000000..33da6cba4dab
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+++ b/source/isaaclab_visualizers/test/conftest.py
@@ -0,0 +1,134 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Diagnostic instrumentation for ViewerGL.get_frame.
+
+Logs context state and the PBO/CUDA-GL interop result so we can tell whether
+the FBO itself is empty (rendering didn't happen) or whether the PBO/CUDA
+readback path returned zeros while the FBO had content.
+
+The instrumentation is installed via pytest_collection_modifyitems so Newton
+is imported AFTER the test file has run AppLauncher (which sets up Kit's pxr
+bindings). Importing Newton at conftest top-level pulls pxr in too early and
+causes a TypeError on Kit 110+ ("No to_python converter for GfVec3f").
+"""
+
+from __future__ import annotations
+
+import ctypes
+
+
+def _gl_err_str(code):
+    names = {
+        0: "GL_NO_ERROR",
+        0x0500: "GL_INVALID_ENUM",
+        0x0501: "GL_INVALID_VALUE",
+        0x0502: "GL_INVALID_OPERATION",
+        0x0503: "GL_STACK_OVERFLOW",
+        0x0504: "GL_STACK_UNDERFLOW",
+        0x0505: "GL_OUT_OF_MEMORY",
+        0x0506: "GL_INVALID_FRAMEBUFFER_OPERATION",
+    }
+    return names.get(int(code), f"0x{int(code):04x}")
+
+
+def _log_environment_once():
+    try:
+        import sys
+
+        import newton as nt
+        import warp as wp
+
+        print(f"[VIZDIAG] python={sys.version.split()[0]}", flush=True)
+        print(f"[VIZDIAG] warp={wp.__version__}  newton={nt.__version__}", flush=True)
+        try:
+            import pyglet
+
+            print(f"[VIZDIAG] pyglet={pyglet.version}  headless={pyglet.options.get('headless')}", flush=True)
+        except Exception as exc:
+            print(f"[VIZDIAG] pyglet info error: {exc}", flush=True)
+    except Exception as exc:
+        print(f"[VIZDIAG] env-log error: {exc}", flush=True)
+
+
+def _instrument_viewergl_once():
+    try:
+        from newton._src.viewer.viewer_gl import ViewerGL
+    except ImportError:
+        return
+
+    if getattr(ViewerGL, "_vizdiag_instrumented", False):
+        return
+
+    original_get_frame = ViewerGL.get_frame
+
+    def instrumented_get_frame(self, target_image=None, render_ui=False):
+        import numpy as np  # noqa: PLC0415
+
+        from newton._src.viewer.gl.opengl import RendererGL  # noqa: PLC0415
+
+        gl = RendererGL.gl
+        prefix = "[VIZDIAG]"
+
+        if not getattr(ViewerGL, "_vizdiag_env_logged", False):
+            _log_environment_once()
+            ViewerGL._vizdiag_env_logged = True
+
+        try:
+            fbo = self.renderer._frame_fbo
+            w, h = self.renderer._screen_width, self.renderer._screen_height
+        except Exception as exc:
+            print(f"{prefix} renderer state error: {exc}", flush=True)
+            return original_get_frame(self, target_image=target_image, render_ui=render_ui)
+
+        print(f"{prefix} fbo={fbo!r}  pbo={self._pbo!r}  wp_pbo={self._wp_pbo!r}  size={w}x{h}", flush=True)
+        e0 = gl.glGetError()
+        print(f"{prefix} glGetError before: {_gl_err_str(e0)}", flush=True)
+
+        # Direct CPU readback of the FBO (independent of the PBO/CUDA path).
+        try:
+            assert fbo is not None
+            cpu_buf = (ctypes.c_uint8 * (w * h * 3))()
+            gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, fbo)
+            gl.glPixelStorei(gl.GL_PACK_ALIGNMENT, 1)
+            gl.glReadPixels(0, 0, w, h, gl.GL_RGB, gl.GL_UNSIGNED_BYTE, cpu_buf)
+            cpu_err = gl.glGetError()
+            cpu_arr = np.frombuffer(cpu_buf, dtype=np.uint8)
+            cpu_nonzero = int((cpu_arr != 0).sum())
+            cpu_max = int(cpu_arr.max()) if cpu_arr.size else 0
+            print(
+                f"{prefix} CPU-readback: nonzero={cpu_nonzero}/{w * h * 3}  max={cpu_max}  "
+                f"first12={cpu_arr[:12].tolist()}  err={_gl_err_str(cpu_err)}",
+                flush=True,
+            )
+            gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, 0)
+        except Exception as exc:
+            print(f"{prefix} CPU-readback error: {exc}", flush=True)
+
+        result = original_get_frame(self, target_image=target_image, render_ui=render_ui)
+        e1 = gl.glGetError()
+        print(f"{prefix} glGetError after: {_gl_err_str(e1)}", flush=True)
+
+        try:
+            arr = result.numpy()
+            nonzero = int((arr != 0).sum())
+            print(
+                f"{prefix} PBO-result: shape={arr.shape}  nonzero={nonzero}/{arr.size}  "
+                f"max={int(arr.max()) if arr.size else 0}  first12={arr.reshape(-1)[:12].tolist()}",
+                flush=True,
+            )
+        except Exception as exc:
+            print(f"{prefix} PBO-result sample error: {exc}", flush=True)
+
+        return result
+
+    ViewerGL.get_frame = instrumented_get_frame
+    ViewerGL._vizdiag_instrumented = True
+    print("[VIZDIAG] ViewerGL.get_frame instrumented", flush=True)
+
+
+def pytest_collection_modifyitems(config, items):  # noqa: ARG001
+    """Hook fires after test files are collected (i.e., after AppLauncher in test files runs)."""
+    _instrument_viewergl_once()